Question

a 30hp,240V, 1150 r/min shunt motor operating at rated conditions has an efficiency of 88.5 percent. The motor parameters are Ra=0.064 ohm RIP=0.0323 ohm and Rf=93.6 ohm. Determine(a) rated shaft torque, (b) mechanical power developed, (c) developed torque at rated value,(d) external resistance required in series with the armature circuit to limit the loacked rotor current to 175 percent rated armature curent, (e) developed torque for the conditions in part (d)